The present invention relates to the chemical cleaning arts. It finds particular application in conjunction with the removal of baked on residues from sterilizers, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to the cleaning of residues from other processing equipment, such as pharmaceutical, food, and beverage equipment, and the like.
Steam sterilizers are generally operated at a pressure of about 2 kg/sq. cm (30 psi) and a temperature of around 130xc2x0 C. Over a period of time, the chamber walls become coated with a residue comprising baked on materials, such as boiler compounds, lint, debris, tape and packaging materials used to wrap medical devices being sterilized. These residues interfere with the efficient operation of the sterilizer or may be dislodged from the chamber walls and soil the sterilized items.
The baked on residues are difficult to remove. Mechanical methods have been used to remove the residue, but these are labor intensive. It takes approximately 6-8 hours to mechanically clean one sterilizer. In one method, the chamber walls are blasted with a stream of glass beads. An air compressor, which is parked outside the facility and connected to the glass bead equipment by a long air line, powers the equipment. The chamber is tented to contain the beads and dust generated. A ventilation hood, supplied by a separate air compressor, is worn by the operating technician. The surface of the chamber walls is often left in a roughened condition which is difficult to polish to a smooth finish.
In another method, a hand-held grinding/polishing wheel and an abrasive compound are used to remove the residue. The grinding wheel is usually powered by an air compressor, as for the glass bead method. The sterilizer is tented to contain dust generated in the process and breathing equipment is worn by the technician performing the cleaning. In the process, weld joints and studs in the sterilizer may be damaged and additional time is taken to repair the damage. For nickel plated sterilizer chambers, the polishing process may remove the thin nickel plating (typically around 0.5 millimeters in thickness, or less) exposing the underlying carbon steel to subsequent corrosion. On stainless steel sterilization chambers, damage to weld joints is a problem.
The present invention provides a new and improved method and cleaning composition for cleaning baked-on residue from a vessel which overcomes the above-referenced problems and others.
In accordance with one aspect of the present invention, a method for cleaning residue from a surface of a sterilizer chamber is provided. The method includes contacting the surface with an alkaline cleaning composition which consists of between about 10 and 30% of an alkaline component and water. The method further includes separately contacting the surface with an acid cleaning composition which consists of between about 10 and 55% of an acid component and water. The steps of contacting the surface with the acid and the alkaline cleaning compositions are carried out for sufficient time to substantially clean the surface of residue.
In accordance with another aspect of the present invention, a two part composition for removing baked-on residues from a surface is provided, the residues comprising both organic and inorganic substances. The composition includes a cleaning solution for removing the organic substance which includes between about 10 and 30% of an alkaline component, 0.1-5% of a surfactant, 3-20% of a chelating agent, and water. The composition further includes a cleaning solution for removing the inorganic substance which includes between about 10 and 55% of an acid component, 0.1-5% of a surfactant, 0.2-10% of a chelating polymer, and water.
One advantage of the present invention is the provision of an easily portable cleaning system.
Another advantage of the present invention is that a sterilizer is cleaned and ready to be returned to service in about two to four hours.
Yet another advantage of the present invention is that the cleaning compositions are contained within the system and pose few hazards to operating technicians.
A further advantage of the present invention is that a neutralized product is formed after cleaning which may be disposed in the normal waste system.
A yet further advantage of the present invention is that the cleaning compositions do not have a significant negative influence on the nickel plate on the sterilizer walls.
A still yet further advantage of the present invention is that the system is adaptable to a variety of sterilizer shapes and sizes.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.